Adjusting linear correction - AQT530

AQT530 Configuration Guide
Document code
M212572EN
Revision
E
Language
English
Product
AQT530
Document type
User guide

Span and zero values are used for the linear correction of the measured values. Zero parameter corrects the offset and span the sensitivity (gain).

You can set the zero and span correction for gas and particle measurements.

The adjusted values affect the measured values of the following Modbus register addresses.

To adjust the span and zero through the Modbus interface, use registers 0086h - 0097h.

Table 1. Modbus registers for measurement data
Address Description
0000h - 0006h Gas concentrations in parts per billion (ppb) with linear correction
0066h - 006Bh Gas concentrations in μg/m3 with linear correction

0008h - 0009h

0037h

 Particle matter PM1, PM2.5, and PM10 in μg/m3 with linear correction

After making these changes, AQT530 outputs data corrected by these zero and span correction factors.

Table 2. Linear correction parameters - gases
Parameter Type Range Default Unit Description
co_zero int16 −10000 ...  10000 0 ppb CO sensor zero correction
co_span uint8 1 ... 255 100 % CO sensor span correction (1 ... 255 = 0.01 ... 2.55)
no_zero int16 −10000 ...  10000 0 ppb NO sensor zero correction
no_span uint8 1 ... 255 100 % NO sensor span correction (1 ... 255 = 0.01 ... 2.55)
no2_zero int16 −10000 ...  10000 0 ppb NO2 sensor zero correction
no2_span uint8 1 ... 255 100 % NO2 sensor span correction (1 ... 255 = 0.01 ... 2.55)
so2_zero int16 −10000 ...  10000 0 ppb SO2 sensor zero correction
so2_span uint8 1 ... 255 100 % SO2 sensor span correction (1 ... 255 = 0.01 ... 2.55)
h2s_zero int16 −10000 ...  10000 0 ppb H2S sensor zero correction
h2s_span uint8 1 ... 255 100 % H2S sensor span correction (1 ... 255 = 0.01 ... 2.55)
o3_zero int16 −10000 ...  10000 0 ppb O3 sensor zero correction
o3_span uint8 1 ... 255 100 % O3 sensor span correction (1 ... 255 = 0.01 ... 2.55)
Table 3. Linear correction parameters - particles
Parameter Type Range Default Unit Description
pm1_zero int16 −10000 ...  10000 0 0.1 μg/m3 PM1 offset (zero) correction (−10000 ... 10000 = −1000.0 ... 1000.0)
pm1_span int16 1 ...  10000 1000 ‰ PM1 span (gain) correction (1 ... 10000 = 0.001 ... 10.000)
pm25_zero int16 −10000 ...  10000 0 0.1 μg/m3 PM2.5 offset (zero) correction (−10000 ... 10000 = −1000.0 ... 1000.0)
pm25_span int16 1 ...  10000 1000 ‰ PM2.5 span (gain) correction (1 ... 10000 = 0.001 ... 10.000)
pm10_zero int16 −10000 ...  10000 0 0.1 μg/m3 PM10 offset (zero) correction (−10000 ... 10000 = −1000.0 ... 1000.0)
pm10_span int16 1 ...  10000 1000 ‰ PM10 span (gain) correction (1 ... 10000 = 0.001 ... 10.000)
  1. Establish a connection to AQT530.
  2. Adjust the gain and offset of the parameters.

    For example, to adjust offset up by 100 ppb and sensitivity 1.2 times (120 %) higher, type:

    set o3_zero=100
set o3_span=120
  3. To save the changes: 
    write --really

    The new values overwrite the previous zero and span values.

Values without linear correction are available with Modbus registers 006Ch - 0075h.